Titanium/titanium alloy-and-resin composite and method for making the same

ABSTRACT

A titanium/titanium alloy-and-resin composite includes a titanium/titanium alloy substrate, a nano-porous oxide film formed on the substrate, and resin compositions coupled to the surface of the nano-porous oxide film. The nano-porous oxide film has nano pores and includes at least two layers of different three dimensional meshed structures. The resin compositions contain crystalline thermoplastic synthetic resins. A method for making the titanium/titanium alloy-and-resin composite is also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is one of the two related co-pending U.S. patentapplications listed below. All listed applications have the sameassignee. The disclosure of each of the listed applications isincorporated by reference into another listed application.

Attorney Docket No. Title Inventors US 39535 TITANIUM/TITANIUMALLOY-AND- HUANN-WU RESIN COMPOSITE AND METHOD CHIANG et al. FOR MAKINGTHE SAME US 39536 TITANIUM/TITANIUM ALLOY-AND- CHENG-SHI RESIN COMPOSITEAND METHOD CHENN et al. FOR MAKING THE SAME

BACKGROUND

1. Technical Field

The present disclosure relates to titanium/titanium alloy-and-resincomposites, particularly to a titanium/titanium alloy-and-resincomposite having high bonding strength between titanium/titanium alloyand resin and a method for making the composite.

2. Description of Related Art

Adhesives, for combining heterogeneous materials in the form of a metaland a synthetic resin are in demand in a wide variety of technicalfields and industries, such as the automotive and household appliancefields. However, the bonding strength of the metal and resin is weak.Furthermore, adhesives are generally only effective in a narrowtemperature range of about −50° C. to about 100° C., which means theyare not suitable in applications where operating or environmentaltemperatures may fall outside the range. Due to the above reason, otherbonding methods have been applied that do not involve the use of anadhesive. One example of such methods is by forming bonds throughinjection molding or other similar process. However, the bondingstrength of the metal and resin can be further improved.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE FIGURES

Many aspects of the disclosure can be better understood with referenceto the following figures. The components in the figures are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the disclosure. Moreover, in thedrawings like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a cross-sectional view of an exemplary embodiment of atitanium/titanium alloy-and-resin composite.

FIG. 2 is a scanning electron microscopy view of an exemplary embodimentof a titanium/titanium alloy substrate being anodized.

FIG. 3 is a cross-sectional view of an exemplary embodiment of atitanium/titanium alloy substrate being electrochemically treated.

FIG. 4 is a cross-sectional view of a mold of the composite shown inFIG. 1.

DETAILED DESCRIPTION

FIG. 1 shows a titanium/titanium alloy-and-resin composite 100 accordingto an exemplary embodiment. The titanium/titanium alloy-and-resincomposite 100 includes a titanium/titanium alloy substrate 11, anano-porous oxide film 12 formed on the substrate 11, and resincompositions 13 formed on the nano-porous oxide film 12.

The nano-porous oxide film 12 is titanium dioxide film. In thisembodiment, the nano-porous oxide film 12 is formed by electrochemicaltreating the substrate 11 first, and then anodizing the substrate 11.

Referring to FIG. 2, the nano-porous oxide film 12 defines nano-pores125. Referring also to FIG. 1, the nano-porous oxide film 12 includes atleast two layers of different three-dimensional meshed structures. Thetwo layers are inner layer 121 near to the substrate 11 and surfacelayer 123 far from the substrate 11. The nano-porous oxide film 12 has atotal thickness of about 300 nm-500 nm, and the surface layer 123 has athickness of about 80 nm-120 nm. The nano-pores of the inner layer 121and the nano-pores of the surface layer 123 have different porediameters. The pore diameter of the nano-pores of the inner layer 121may be at a range of about 20 nm-50 nm. The pore diameter of thenano-pores of the surface layer 123 may be at a range of about 100nm-150 nm.

The resin compositions 13 may be coupled to the surface of thenano-porous oxide film 12 by molding. During the molding process, moltenresin coats the surface of the nano-porous oxide film 12 and fills thenano-pores 125, thus strongly bonding the resin compositions 13 to thenano-porous oxide film 12 and the substrate 11. Compared to theconventional injection molding process in which the titanium/titaniumalloy substrate is not electrochemically treated and anodized, thecomposite 100 in this exemplary embodiment has a much stronger bondbetween the resin compositions 13 and the substrate 11 (about quintuplethe bonding force). The resin compositions 13 may be made up ofcrystalline thermoplastic synthetic resins having high fluidity. In thisexemplary embodiment, polyphenylene sulfide (PPS) and polyamide (PA) canbe selected as the molding materials for the resin compositions 13.These resin compositions 13 can bond firmly with the nano-porous oxidefilm 12 and the substrate 11.

It is to be understood that auxiliary components may be added to theresins to modify properties of the resin compositions 13, for example,fiberglass may be added to PPS. The fiberglass may have a masspercentage of about 30% with regard to the PPS and the fiberglass.

A method for making the composite 100 may include the following steps:

The titanium/titanium alloy substrate 11 is provided.

The substrate 11 is ultrasonic cleaned using anhydrous ethanol andacetone respectively, and then rinsed.

The substrate 11 is electrochemically treated. The electrochemicaltreating process may be carried out in an acid water solution containingsulfuric acid, or an acid water solution of sulfuric acid, with thesubstrate 11 being a cathode, and a stainless steel board being ananode. The sulfuric acid may have a molar concentration of about 0.5mol/L-2 mol/L. The electric current density through the acid watersolution is about 0.1 ampere per square decimeter (A/dm²)-5 A/dm².Electrochemical treating the substrate 11 may last for about 1 minute-10minutes. Once electrochemically treated, a titanium hydride (TiH₂) layer14 is formed on the substrate 11 (referring to FIG. 3). The titaniumhydride layer 14 has a thickness of about 80 nm-120 nm, and a surfaceroughness (Ra) of about 0.3 μm-0.5 μm. Next, the substrate 11 having thetitanium hydride layer 14 is rinsed in water and then dried.

The substrate 11 having the titanium hydride layer 14 is anodized toform the nano-porous oxide film 12. The anodizing process may be carriedout in an alkaline water solution containing sodium hydroxide (NaOH), oran alkaline water solution of sodium hydroxide, with the substrate 11being an anode, and a stainless steel board being a cathode. The sodiumhydroxide may have a molar concentration of about 4.5 mol/L-5.5 mol/L.The electric current density through the alkaline water solution isabout 1-30 A/dm². Anodizing the substrate 11 may last for about 1minute-10 minutes. Once anodized, the nano-porous oxide film 12 isformed on the substrate 11. Next, the substrate 11 having thenano-porous oxide film 12 is rinsed in water and then dried.

During the anodizing process, the titanium hydride layer 14 is firstconverted to titanium dioxide and forms the surface layer 123 of thenano-porous oxide film 12. When the titanium hydride layer 14 iscompletely converted to titanium dioxide, the anodizing process iscontinued on the substrate 11 and forms the inner layer 121 of thenano-porous oxide film 12.

In the exemplary embodiment, the electrochemical treating process andthe anodizing process are all carried out at a room temperature, thatis, the acid and the alkaline water solutions are not heated.

The thickness of the titanium hydride layer 14 in this embodiment isonly an example. The thickness of the titanium hydride layer 14 can bechanged by adjusting the concentration of the acid water solution, theelectric current density, and the lasting time of the electrochemicaltreating process.

The structure and relative characters of the nano-porous oxide film 12in this embodiment is only an example. The structure and the charactersof the nano-porous oxide film 12 can be changed by adjusting theconcentration of the alkaline water solution, the electric currentdensity, and the lasting time of the anodizing process.

The thicknesses of the inner layer 121 and the surface layer 123 of thenano-porous oxide film 12, and the pore diameter of the nano pores 125can be changed by adjusting the parameters of the electrochemicaltreating process and the anodizing process. Furthermore, by adjustingthe treatment parameters, a nano-porous oxide film having more than twolayers of different three dimensional meshed structures can also obtain.

Referring to FIG. 4, an injection mold 20 is provided. The injectionmold 20 includes a core insert 23 and a cavity insert 21. The coreinsert 23 defines several gates 231, and several first cavities 233. Thecavity insert 21 defines a second cavity 211 for receiving the substrate11. The substrate 11 having the nano-porous oxide film 12 is located inthe second cavity 211, and molten resin is injected through the gates231 to coat the surface of the nano-porous oxide film 12 and fill thenano-pores 125, and finally fill the first cavities 233 to form theresin compositions 13, as such, the composite 100 is formed. The moltenresin may be crystalline thermoplastic synthetic resins having highfluidity, such as PPS, or PA.

The shear strength of the composite 100 has been tested. The testsindicated that the shear strength of the composite 100 was 19 MPa-27MPa. Furthermore, the composite 100 has been subjected to a temperaturehumidity bias test (72 hours, 85° C., relative humidity: 85%) and athermal shock test (48 hours, −40° C.-85° C., 4 hours/cycle, 12 cyclestotal), such testing did not result in decreased shear strength of thecomposite 100.

It is believed that the exemplary embodiment and its advantages will beunderstood from the foregoing description, and it will be apparent thatvarious changes may be made thereto without departing from the spiritand scope of the disclosure or sacrificing all of its advantages, theexamples hereinbefore described merely being preferred or exemplaryembodiment of the disclosure.

1. A titanium/titanium alloy-and-resin composite, comprising: atitanium/titanium alloy substrate; a nano-porous oxide film formed onthe substrate, the nano-porous oxide film having nano pores andcomprising at least two layers of different three dimensional meshedstructures; and at least a resin composition integrally coupled to thesurface of the nano-porous oxide film, the resin composition containingcrystalline thermoplastic synthetic resins.
 2. The composite as claimedin claim 1, wherein the nano-porous oxide film is titanium dioxide film.3. The composite as claimed in claim 1, wherein the at least two layershave nano pores with different pore diameters ranges.
 4. The compositeas claimed in claim 3, wherein the at least two layers comprising aninner layer near to the substrate and a surface layer far from thesubstrate, the inner layer has nano pores having a pore diameter at arange of about 20 nm-50 nm, the surface layer has nano pores having apore diameter at a range of about 100 nm-150 nm.
 5. The composite asclaimed in claim 4, wherein the nano-porous oxide film has a totalthickness of about 300 nm-500 nm, the surface layer has a thickness ofabout 80 nm-120 nm.
 6. The composite as claimed in claim 4, wherein theresin composition fills the nano-pores of the inner layer and thesurface layer.
 7. The composite as claimed in claim 1, wherein the resincomposition is molded crystalline thermoplastic synthetic resincomposition.
 8. The composite as claimed in claim 1, wherein thecrystalline thermoplastic synthetic resin is polyphenylene sulfide orpolyamide.
 9. The composite as claimed in claim 1, wherein thecrystalline thermoplastic synthetic resin is polyphenylene sulfide addedwith fiberglass, the fiberglass has a mass percentage of about 30% withregard to the polyphenylene sulfide and the fiberglass.
 10. A method formaking a titanium/titanium alloy-and-resin composite, comprising:providing a titanium/titanium alloy substrate; electrochemicallytreating the substrate to form a titanium hydride layer on a surfacethereof; anodizing the substrate having the titanium hydride layer toform an nano-porous oxide film on the surface of the substrate, thenano-porous oxide film having nano pores and comprising at least twolayers of different three dimensional meshed structures; and insertingthe substrate in a mold and molding crystalline thermoplastic syntheticresin on the surface of the nano-porous oxide film to form thecomposite.
 11. The method as claimed in claim 10, whereinelectrochemically treating the substrate is carried out in an acid watersolution containing sulfuric acid for about 1-10 minutes with thesubstrate being a cathode, the mol concentration of the sulfuric acid isabout 0.5-2 mol/L, the electric current density through the acid watersolution is about 0.1-5 A/dm².
 12. The method as claimed in claim 11,wherein the titanium hydride layer has a thickness of about 80 nm-120 nmand a surface roughness of about 0.3 μm-0.5 μm.
 13. The method asclaimed in claim 10, wherein anodizing the substrate is carried out inan alkaline water solution containing sodium hydroxide for about 1-10minutes with the substrate being an anode, the mol concentration of thesodium hydroxide is about 4.5-5.5 mol/L, the electric current densitythrough the alkaline water solution is about 1-30 A/dm².
 14. The methodas claimed in claim 10, wherein the crystalline thermoplastic syntheticresin is polyphenylene sulfide or polyamide.
 15. The method as claimedin claim 10, wherein the crystalline thermoplastic synthetic resin ispolyphenylene sulfide added with fiberglass, the fiberglass has a masspercentage of about 30% with regard to the polyphenylene sulfide and thefiberglass.
 16. The method as claimed in claim 10, wherein thenano-porous oxide film is titanium dioxide film.
 17. The method asclaimed in claim 10, wherein the at least two layers comprising an innerlayer near to the substrate and a surface layer far from the substrate,the inner layer has nano pores having a pore diameter at a range ofabout 20 nm-50 nm, the surface layer has nano pores having a porediameter at a range of about 100 nm-150 nm.
 18. The method as claimed inclaim 17, wherein the nano-porous oxide film has a total thickness ofabout 300 nm-500 nm, the surface layer has a thickness of about 80nm-120 nm.
 19. The method as claimed in claim 17, wherein the resincomposition fills the nano-pores of the inner layer and the surfacelayer.
 20. A titanium/titanium alloy-and-resin composite, comprising: atitanium/titanium alloy substrate; a nano-porous oxide film formed onthe substrate, the nano-porous oxide film having nano pores andcomprising at least two layers of different three dimensional meshedstructures; and at least a resin composition integrally molded to thesurface of the nano-porous oxide film, the resin composition containingcrystalline thermoplastic synthetic resins.